High-speed digital printing systems, of which an example is the Indigo printing system by Hewlett-Packard Company, have progressed to the point that the output is virtually indistinguishable from the high-quality printing that formerly was associated only with offset lithography. This new digital printing technology uses inks that can be attracted or repelled by a static electric charge. A uniform charge is deposited on an imaging surface by a voltage differential between the electrical ground beneath the imaging surface and a charging element, such as a charge roller. The charge roller comprises a metal shaft coated with an electrically-resistive composition such as polyurethane rubber with additional conductive agents. This rubber coating assures uniform charge distribution on the imaging surface. Then a pattern is formed in the charge on the imaging surface by a scanning laser. Inks of various colors are applied to the imaging surface according to the charge pattern. These patterns of ink are then transferred onto paper. The ink is specially formulated so as not to mask the underlying surface roughness or glossiness of the paper.